Joiner, Scheffer and Kumho: Refining the Standards for Expert Evidence

When the Supreme Court handed down its decision five years ago in the case of Daubert v. Merrell Dow Pharmaceuticals, Inc. (509 U.S. 579 (1993)), many observers wondered whether the Court would really show itself to be serious over the long run about controlling junk science in the courtroom. An influential body of litigators, after all, was determined to keep pressing for the continued admission of speculative scientific testimony. Justice Harry Blackmun, who wrote the majority opinion in Daubert, proceeded to retire the next year; and perhaps with his departure the majority would fracture, especially given that the controversy had provoked the appearance of a split within the scientific community itself.

In the Court’s 1997-98 term, the Supreme Court made clear there will be no fracture and no retreat. In two separate cases, General Electric v. Joiner and United States v. Scheffer, the Court had occasion to revisit its Daubert holding. Both times, it calmly reaffirmed its 1993 standard. Both decisions were all but unanimous, and one in fact was authored by Chief Justice Rehnquist, who had been one of the two dissenters in Daubert. Joiner and Scheffer help to eliminate any residual doubt there might have been about what Daubert means or what impact it will have. For the remaining defenders of the “let-it-all-in” philosophy of expert admissibility, the news is bad. For the rest of society, this is very good news indeed.

On December 7, the Court will hear oral argument in yet another expert-testimony case, Kumho TireCompany v. Carmichael. That case presents a question that the Court expressly declined to resolve in Daubert: whether the criteria articulated in Daubert itself apply equally in cases involving expert testimony on matters not ordinarily termed "scientific" - the kind of testimony typically offered by engineers, doctors, economists, and appraisers, among others. In an opinion that should be released early next year, the Supreme Court will venture to set them straight.

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The controversy over expert admissibility is important to anyone concerned about America’s continued litigation boom for a simple reason: reliable science crowds out chances to litigate. In civil law, the notion that any cause might produce any consequence generates a maximum of chances to sue every defendant in sight when things go wrong. In criminal law, reliable DNA tests should displace a great amount of courtroom argument over, say, the identities of rapists or of assailants who have left their own blood at a crime scene. Indeed, the growing power of forensic science should not be denied some share of credit in the general success of the war on crime, having made it likelier to bring genuine culprits to justice (even if countervailing factors, such as celebrity and the race card, sometimes make it seem as if it has become easier to get away with murder).

But every victory for genuine science depends on a victory over pseudo- or counter-science. Sometimes this takes a negative form, consisting of unreasonable doubt about true advances such as (properly performed) DNA testing. Sometimes it consists of dubious positive assertions: speculative theories and tortured statistics expand the range of people or things to blame, explanations to proffer, excuses to raise, and doubts to sow. Rather than revealing and affirming “that which is known,” this kind of “science” serves only to increase doubt, uncertainty, and confusion. It subtracts from human knowledge rather than adding to it.

No one, of course, claims to endorse bad science or pseudo-science. But a significant number of thinkers are willing to endorse the notion that it’s somehow unfair to keep from the courtroom the “expert” testimony of those who hold idiosyncratic or unverified views on subjects scientific. After all, the freedom to “speak one’s piece” is rightly treasured in an open society. Why shouldn’t that include the right to reach a jury with such views? The difference, of course, is that a courtroom is not a debating society. It is one thing for a newspaper to print daily horoscopes, quite another to let juries award damages, acquit criminals, or convict innocent people on the strength of evidence that is not reliable.

When the Court agreed to hear the original Daubert case, its importance was so clear that both sides rushed to round up scientists and professional associations to subscribe to friend-of-the-court briefs to support their view of things. The plaintiffs’ view - that federal judges should not endeavor to draw lines between reliable, valid, expert testimony and the many alternatives - curiously managed to attract the signature even of such noted figures as Stephen Jay Gould, the paleontologist and splendid writer who teaches at Harvard. It was a surprising position to take for a man who, in his other life, has argued long and hard against admitting to some sort of parity the claims of evolution on the one hand and “creation science” on the other. Yet if all points of view are as legitimate as all the others and anyone with a Ph. D. deserves an equal chance at the podium, why should it offend to have one brand of biological “science” taught in public schools alongside the most widely accepted one? At any rate, the Court found the amicus brief of Gould et al unpersuasive, and by a vote of 7 to 2 in Daubert announced a far more rigorous standard for admitting expert “scientific knowledge” into federal courts under the Federal Rules of Evidence.

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It is peculiarly fitting that the two cases to come up last term should have revolved around the admissibility of testimony on toxic-tort causation (General Electric v. Joiner) and of polygraph tests (United States v. Scheffer). The two cases that had bracketed the history of the law in this area, after all, were Daubert itself, a case on toxic-causation admissibility, and the 1923 Frye v. United States (293 F. 1013 (D.C. Cir. 1923)), a case on polygraph admissibility.

In Frye, the defendant was accused of murdering a doctor. He had confessed, then recanted. At trial he offered a weak alibi, and also sought to introduce evidence that he had passed a “systolic blood pressure deception test” — a primitive precursor of the “lie detector” polygraph. The trial court rejected this evidence. In affirming that ruling, the D.C. Circuit Court of Appeals articulated a requirement of “general acceptance in the scientific community,” the rule that was to govern the admission of expert testimony in federal courts for the next seven decades, and was to be updated with Daubert.

General Electric v. Joiner was decided in December 1997. Robert Joiner alleged that his small-cell lung cancer was “promoted” by his workplace exposure to PCBs in electrical transformers manufactured by GE. Federal District Judge Orinda D. Evans, Jr. had thrown out the case on summary judgment. The testimony of Joiner’s experts did not rise above “subjective belief or unsupported speculation,” he ruled. The Eleventh Circuit Court of Appeals overturned. It reasoned that appellate courts should be more willing to overturn trial judges who excluded dubious scientific testimony than those who admitted it.

The Supreme Court, in an opinion by Chief Justice Rehnquist, reinstated Judge Evans’ summary judgment in favor of General Electric, ruling that he had acted within his discretion. The views of Joiner’s “experts” were based exclusively on “isolated” animal studies in which massive doses of PCBs had been injected directly into the stomachs of infant mice. One expert had admitted that no study had demonstrated that PCBs lead to cancer in any other species. “The studies were so dissimilar to the facts presented in this litigation that it was not an abuse of discretion for the District Court to have rejected the experts’ reliance on them,” Chief Justice Rehnquist concluded. And individually or in combination, four human epidemiological studies also cited by Joiner’s experts lent no support to Joiner’s claims.

Three months later, in March, the Court handed down its decision in United States v. Scheffer. Justice Thomas wrote the opinion in an 8-1 ruling. Edward Scheffer, an airman at March Air Force base in California, had volunteered to work as an undercover informant in the Air Force’s drug investigations. He had been advised he would be periodically tested for drug use and examined by polygraph. A month later he had submitted a urine sample, taken and passed a polygraph test–and had then gone AWOL, disappeared in fact. He was caught, returned to base, and his urinalysis revealed methamphetamines. Scheffer claimed “innocent ingestion” and sought to introduce the polygraph evidence, which had indicated “no deception.” At issue in the case was Military Rule of Evidence 707, which excludes polygraph evidence from all court-martial proceedings. The rule unconstitutionally abridged his right to present a defense, Scheffer argued.

Only Justice Stevens agreed. He pointed to “a host of studies that place the reliability of polygraph tests at 85 percent to 90 percent.” Even critics “place polygraph accuracy at 70 percent.” Moreover, polygraphs are more likely to find innocent people guilty than vice versa. Hence, exculpatory polygraphs are “likely to be more reliable than inculpatory ones.”

Such figures notwithstanding, eight Justices concluded that Rule 707 serves the legitimate and important interest of ensuring that only reliable evidence is introduced at trial. There is no scientific consensus that polygraph evidence is reliable. Excluding such evidence is therefore “a rational and proportional means of advancing the legitimate interest in barring unreliable evidence.”

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When Justice Blackmun, the author of Daubert, retired from the Court in 1994, President Clinton nominated Justice Stephen Breyer to succeed him. While he joined the Chief Justice’s majority opinion in Joiner, Justice Breyer also added a concurring opinion of his own. He did so to emphasize Daubert’s statement that a trial judge, acting as “gatekeeper,” must “ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.” Judges may not act as scientists, Justice Breyer observed, but neither the difficulty of the task nor any comparative lack of expertise can excuse the judge from exercising the “gatekeeper” duties that the Federal Rules of Evidence impose. The trial judge must ascertain whether proffered expert testimony is reliable, whether it will “assist” the jury, and whether the “probative value” of testimony is substantially outweighed by risks of prejudice, confusion or waste of time. “I therefore want specially to note that, as cases presenting significant science-related issues have increased in number,” Justice Breyer concluded, “judges have increasingly found in the Rules of Evidence and Civil Procedure ways to help them overcome the inherent difficulty of making determinations about complicated scientific or otherwise technical evidence.”

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So what should we expect the Court to do in Kumho? At issue in Kumho: is the testimony of a "tire failure expert." The challenged expert claimed to be able to tell whether a blown tire had failure because of a defect in its manufacture or because of underinflation, overloading, or other abuse. His conclusions were based, he asserted, on a visual inspection of the tire and long personal experience.

Applying Daubert, the trial judge ruled that Dennis Carlson's testimony was inadmissible, and entered summary judgment for the defendant. The Eleventh Circuit Court of Appeals overturned, on the ground that while some elements of Daubert are relevant to expert testimony of this kind, others aren't. Of the nine circuits that have ruled on that question, three others align with the Eleventh, while five have concluded Daubert should apply without modification.

Our guess: the Court will reaffirm Daubert's core requirements that expert testimony must be objective, testable, reliable, and not too prone to error, while recognizing that how those requirements are enforced will vary from one field to the next. As stated in the amicus submitted by the National Academy of Engineering: “Expert testimony in engineering, just like expert testimony in the sciences, should be admitted only if the testimony is found to have a reliable basis in the knowledge and experience of the engineering discipline. Testimony that is not rooted in such knowledge and experience is at best useless, and at worst misleading to the trier of fact.” The Academy argues that the specific criteria in Daubert are appropriate and useful for engineering testimony.

The cleanest possible win for Kumbo defendants would be for the Supreme Court to reinstate the summary judgment entered originally by the trial judge. That might happen - several of the Justices are strongly predisposed to leave such matters to the discretion of trial judges, and trial judges have been working things out tolerably well under the Daubert framework. But at least equally possible is a remand of some sort, as occurred in Daubert itself. The expertise of exploding tires is not quite the same as the expertise of morning sickness drugs, the Justices may conclude, and the reliability of tire testimony must therefore be weighed on a somewhat different balance. If that happens, the case will head back to the trial judge - who will have to decide anew whether or not to admit the challenged testimony.

Either way, however, the principles of Daubert will remain secure. The Court that has closed the gate on junk science is not about to throw it open to junk engineering, economics, or medicine.

Peter Huber, a lawyer with a doctorate in engineering, is a Senior Fellow at the Manhattan Institute; author of Law & Disorder in Cyberspace, Judging Science, Galileo's Revenge, and Liability; and he is a columnist for Forbes magazine as well as a contributing editor at Reason magazine, in which this piece first appeared.